Break-key.



J. L. HOGAN, 3P.. BREAK KEY.

APPLICATION FILED SEPT. 9, 1910.

ra srv/7CH 4 Patented Feb.6,1l92.

uNiTi'iD sTATns PATENT 'onirica JOHN L. HGAN, JR., OF BRANT ROCK, MASSCHUSETTS, ASSIGNR TO NTIONAL ELECTRC SIGNALLING COMANY, OF PITTSBURGH, PENNSYLVANIA., A/CRPOEA- Tron or New JERSEY.

:BREAK-KEY.

Patented rea. 6.1912.

application tiled September 9, 1910. Serial No. 581,333.

T o all when, z'z may concern:

Ee it known that l, JOHN L. HOGAN, Jr., a citizen of the'United States, residing at Brant Rock, in the State of Massachusetts, have invented a certain new and yuseful Break-Key for Telegraph Apparatus, ot which the following is a specification.

My invention relates to electric signaling apparatus, and especially to apparatusfor.

Wireless signaling in which there are associated with the same antenna both a sending circuit and a receiving circuit.

The primary object of the invention-is to provide mechanism by which the sending key,`in the operation of sending, Aautomati-l cally isolates the receiving instruments and protects the operator and the receiving circuit frorn injury by the source of power.

I have illustrated the invention in one simple form in the accompanying drawing, in which Figure 1 is a diagram of associated sending and receiving circuits for wireless telegraphy, with switches embodying my invention. Fig. 2 'is a plan of I'witch employed.

it .is manifestly desirable for a telegraph operatorengaged in sending messages to be able at practically the same time to listen to messages being sent by others, tor various reasons; at the same time 1t 1s dangerous to have the receivin`g circuit or instrumentsconnected to the antenna while sending and in using high power sending apparatus it has become quite necessary to insure the operator against injury that might, result from having both the sending and receiving apparatus simultaneously connected to t-he antenna. The receiving apparatus oilght' to -be completely and with certainty isolated from the antenna while sending; and while it has been heretofore attempted by shunting some part of the receiver circuits by means of a break lrey,lthis does not isolate the receiver, and moreover is open to the objection that an incomplete closure of the shunting switch would leave the receiver exposed. to full charge from the antenna. Entire safety and certainty are only to be attained by so arranging it that the act of depressing the sending key will, before connecting the sending circuit at all, necessarily and completely isolate the receiving circuit;

1n the form of apparatus shown in the the protecting drawinigor.illustration, the source of current 3, 1s in circuit with a magnetically operated switch 4 and the primary 5 of a` antenna. 11. `When sending, the antennacircuit is completed to ground 12 through.

shunt 13 and the variable inductance coil 14. But this circuit cannot be completedf.

until both the switch lever arms 15 and 16 are in contact with the sliuntl, at which time the rear ends of said' lever arms are in contact with a second shunt 17 in circuit with battery 18 and the solenoid 19 operating switch 4 in the primary circuit. c There-A 'fore it is plain that only when.. this latter condition is 'obtained can `the energy Yfrom the source be transmitted to the antenna.

rIfhe receiving circuit, shown simplified forpurposes of illustration, consists of the inductance coils 20, condenser 21., and the detector ll. This circuit is connected with the.; antenna only when the switch arms 15 and 16 are drawn by theirretractile springs to rest respectively on the contacts 23 and 24. i The operating key 25 is in' circuit wit-h a battery 26 and an electromagnet 27, varranged to act upon armatures 28 and 29 onA the switches 15 and 16 respectively, so that' the act of closing the key 25 energizes the solenoid 27v and moves theser arms to close the shunt 13 as heretofore'described. 'A simple form of construction for these switches and their mountings, is shown in F ig. 2. It will be observed that ot' closing the signaling key 25 iE iirst to eut out the receiving circuit, and that until this'is done, so as to completely isolate the receiver from the antenna circuit, the arms 15 and 1G can not Aclose on theshunt 13, so as to ground the antenna direct rather than through the receiver,`nor can the shunt 17 Ibe connected so as to allow the solenoid 19 -to close-the switch livcompleting the primary sending cireuit. It is therefore ime eil'ect possible for the latter circuit to be closed, or

the antenna to be charged, until after lthe receiving circuit has been isolated and both the instruments and the operator thereby protected. As an additional precaution I' prefer -also to shunt the detector R, as for example bv means of a switch 30 operated by solenoid 3l in the'same circuit with the antenna and ground connections, then to sending key 25 and battery 26. Thiais for the purpose of protecting the receiver vtrom y anyv oscillations that might be picked up' 5 fronilthe sendinginductances by the receiving tuning apparatus, even though `the latter be conductively isolated.

Q .Th'e device described does not depend upon the erfection of contact 'of any L0 switch; the isolation of the receiving in-l struments 1s accomplished as a necessary ,preliminary to the act of closing'the send- .ing circuit, by which the antenna is energized. The invention 1s not. limited to the .15Vparticular mechanism here described for doing this.

Having thus described my invention and illustrated itsuse, what I claim as new and desire to secure by Letters Patent, is the a0 following 1. The combination with a sending circuit and a receiving oscillating circuit and an antenna associated with both said circuits, of a break key adapted to entirely l isolate the receiving circuit from the an.-

tenna from groundand afterward close the sending circuit, whereby the antenna is en- -ergized, substantially as described.

I 2. Inv wireless telegraph apparatus, thecombination with a vsending circuit and a sending key, of a` receiving apparatus and a switch operated by the sending key to cut off the receiving oscillation' circuit from both the Aradiator and the ground before connecting theradiator with the sending circuit. M

3. A break key for wireless telegraph apparatus which includes 'sending and receiving circuits, comprising av switch and means 40 lcontrolled thereby operating to first isolate the receiving circuit by short-circuiting its complete the antennaL circuit and then to close the sending circuit, all in one motion, substantially as described'.

4. A switching device for wireless telegraphy apparatus including sending and receiving oscillation circuits, said device adapted Aand disconnect the receiving oscillation circuit both with the antenna and the ground and the other end of said device adapted to close the sending control circuit after disconnecting the antenna and ground from the receiving oscillation circuit, substantially as described.

5. The combination with a source of power, an oscillatory sending circuit. and a grounded antenna connected therewith, of an oscillating receiving circuit, a sending key and a switch adapted to connect the receiving circuit with the antenna in one position, and in another position to completely isolate the receiving circuit from tie anvtenna and fron.- tlie ground and afterward complete the sending circuit, substantially as described.

6. The combination with a sending circuit andi a receiving circuit, of a break-key and a signaling key located in a circuit inat one end to alternately connect" dependent of the sending circuit, said two keys arranged to Short-circuit and completely isolate the receiving circuit before causing the closure of lthe sending circuit,

substantially as described. 1

In testimony whereof have hereunto signed my name in the presence of the two subscribed witnesses. f f

JoHN'L. HOGAN, JR. Witnesses H. M. CoRwIN, F. W. H. CLAY. 

